This invention relates to a shielding terminal for a coaxial cable, and more particularly to a shielding terminal for a coaxial cable which has a press-clamping portion for being press-fastened to an end portion of the coaxial cable, and is electrically connected to a braid of the coaxial cable exposed at the end portion thereof.
Generally, in order to block electrical noises such as electromagnetic waves and static electricity, a coaxial cable, used as an antenna wire or the like, is constructed that a conductor is covered with an inner insulative covering, the inner insulative covering is covered with a braid, and this braid is covered with an insulative sheath.
There have been proposed various coaxial connectors for connecting such a coaxial cable to a mating equipment or a mating connector.
In such a coaxial connector, there is used a shielding terminal for a coaxial cable which connects the braid of the coaxial cable to the mating connector for grounding purposes. One example of such terminals is shown in FIGS. 4 and 5.
The shielding terminal 1 for the coaxial cable is formed by bending a conductive metal plate as shown in FIGS. 4 and 5, and this terminal includes a terminal body 4 of a rectangular tubular cross-section, formed by a pair of half-split box portions 3, extending upwardly respectively from opposite side edges of a front end portion (left end portion in the drawings) of a terminal bottom plate portion 2, and a press-clamping portion 7 which includes a pair of braid-clamping piece portions 5, extending upwardly respectively from opposite side edges of a rear-side portion (right-side portion in the drawings) of the terminal bottom plate portion 2 so as to be fastened and connected by pressing to a braid 12 of the coaxial cable 10, and a pair of sheath-clamping piece portions 6 (see FIG. 6A) extending upwardly respectively from opposite side edges of a rear end portion (right end portion in the drawings) of the terminal bottom plate portion 2 so as to be fastened and connected by pressing to an insulative sheath 13 of the coaxial cable 10.
An inner terminal (not shown) of a cylindrical shape is press-fastened and connected to that portion of a conductor 14 exposed at an end portion of the coaxial cable 10 by removing part of an inner insulative covering 11, and thereafter the shielding terminal 1 is press-fastened and connected to the end portion of the coaxial cable. Then, the inner terminal, inserted in the terminal body 4 of the shielding terminal 1, is held in an insulative inner housing (not shown), and thereafter the shielding terminal 1 is received and held in a terminal receiving portion of an insulative outer housing (not shown), thus assembling a coaxial connector.
Therefore, when the coaxial connector is fitted into a mating equipment or the like (not shown), the braid 12 is connected to the equipment for grounding purposes via the shielding terminal 1, so that the coaxial cable 10 is electromagnetic shielded.
In the above shielding terminal 1, the press-clamping portion to be press-fastened and connected to the end portion of the coaxial cable 10 includes the braid-clamping piece portions 5 and the sheath-clamping piece portions 6 which are arranged serially at the opposite side edges of the rear end portion of the terminal bottom plate portion 2.
Therefore, when the coaxial cable 10, press-fastened and connected to the shielding terminal 1, is pulled upwardly as indicated in imaginary lines (two doted lines) in FIG. 5, with the coaxial connector fitted in the mating equipment or the like, an external force acts on the sheath-clamping piece portions 6 in a diameter-increasing direction, which leads to a possibility that the pair of press-fastened sheath-clamping piece portions 6 are opened as shown in FIG. 6B.
If the pair of sheath-clamping piece portions 6 are excessively press-fastened in order to secure the clamping force of these sheath-clamping piece portions 6, that portion of the coaxial cable 10, held by the press-clamping portion, is crushed radially, so that the roundness of the braid 12 can not be maintained, and this invites a problem that the characteristic impedance of the coaxial cable would be adversely affected. Therefore, usually, the braid-clamping piece portions 5, as well as the sheath-clamping piece portions 6, are press-fastened, with their distal ends abutted against each other.
If the pair of sheath-clamping piece portions 6 are excessively increased in width in order to secure the clamping force of these sheath-clamping piece portions 6, the overall length of the clamping portion becomes too large, which invites a problem that it is difficult to achieve a compact design of the shielding terminal 1 and a compact design of the outer housing.
It is therefore an object of the present invention to provide a shielding terminal for a coaxial cable which can secure a necessary force of fixing of the terminal to an end portion of the coaxial cable without increasing the size of the terminal.
In order to achieve the above object, according to the present invention, there is provided a shielding terminal for a coaxial cable comprising:
a first clamping portion, which clamps an insulative sheath of the coaxial cable;
a second clamping portion, which clamps a exposed conductive braid portion of the coaxial cable; and
a junction portion, formed integrally between the first clamping portion and the second clamping portion;
wherein the junction portion, extends around an outer periphery of the coaxial cable in which a winding angle of the junction portion with respect to the coaxial cable is not less than 180 degrees, and in which the winding angle of the junction portion is smaller than winding angles of the first clamping portion and the second clamping portion with respect to the coaxial cable respectively.
In the above construction, the first clamping portion to be press-fastened to the sheath of the coaxial cable is formed integrally with the second clamping portion through the junction portion.
Therefore, when an external force acts on the first clamping portion in a diameter-increasing direction, the second clamping portion also resists this external force, acting in the diameter-increasing direction, through the junction portion, and therefore the force of fixing of the terminal with respect to the coaxial cable can be increased.
Preferably, the shielding terminal for a coaxial cable, wherein the winding angles of the first clamping portion and the second clamping portion are substantially 360 degrees respectively. With this construction, the shielding terminal can be more positively fixed to the coaxial cable, and besides the shielding performance is enhanced.